St Peter’s Square in Manchester. The city region will control £1bn of public money and control its own integrated health and social care services. Photograph: Christopher Thomond for the Guardian

Exactly 218 years ago, on 14 May 1787, American politicians gathered in Philadelphia for the first day of the constitutional convention that would, some months later, produce the constitution of the modern US.

This week, on the anniversary of that historic meeting, public leaders from the UK’s 10 core cities meet in London, to launch their own “devolution declaration”. Just as the US convention resulted in the first written US constitution, these leaders, who run cities where almost 19 million people live, want a fundamental rethink of the UK constitution. They are demanding what Sir Richard Leese, leader of Manchester council and chair of the core cities group – Birmingham, Bristol, Cardiff, Glasgow, Leeds, Liverpool, Manchester, Newcastle, Nottingham and Sheffield – calls a “radical modernisation of our centralised state”. This is about giving city-based regions more power to raise money and spend it; more power over planning, transport, homes, schools and health.

On the NHS, where Manchester leads, England’s other cities must follow | Simon Jenkins

Read more

The conference will be led by Leese, still glowing from his success at the helm of the greatest localist coup of the previous parliament: Devo Manc. Agreed in November, this deal between the coalition government and the city region of greater Manchester will see the region, under its new mayor, control £1bn of public money, with powers over transport, housing, planning and policing,and the creation of integrated health and social care services – the so-called “MHS”.

But last week’s election result means that the way forward has become more complex for localists. Leese himself acknowledges that this is a critical moment. Westminster politicians risk being distracted from regional localism by the more urgent issues of Scotland and Europe. SNP leader Nicola Sturgeon is already breathing down the prime minister’s neck, but her focus is on transferring powers from Westminster to Holyrood, rather than to Edinburgh or Glasgow. Whether or not Scotland gets full fiscal autonomy, there is little evidence of Sturgeon being a localist. Glasgow city council’s Labour leader Gordon Matheson, for one, believes the first minister is keen to hold power in Holyrood. So there is little prospect of Scotland’s local authorities getting a similar deal to Manchester’s.

Leese acknowledges that some kind of constitutional process is likely to determine devolution to Scotland, Wales and Northern Ireland, but insists that there should be no delay in unlocking the massive economic potential of cities and other places across the UK. According to the core cities group, the 10 cities’ urban areas deliver 28% of the combined economic output of England, Scotland and Wales. Birmingham city council alone has a budget of more than £3bn a year.

The chancellor, George Osborne, now also first secretary of state, is a keen supporter of the idea of the northern powerhouse, giving it space in his election night speech in his Tatton constituency. His support will be crucial. Talks were already under way between the Treasury and Cardiff over a potential £1bn city deal for the Welsh capital and the new government will be closely watched by regions such as Cornwall and rural counties like Northamptonshire, Oxfordshire and Buckinghamshire, which are keen to avoid the major city regions getting all the money.

According to Ed Cox, of thinktank IPPR North, Conservative plans for English devolution are framed almost entirely in terms of rebalancing the economy, and focus on devolving powers over economic development, transport and social care to large cities, as long as they agree to have directly elected mayors. That’s certainly the model for Greater Manchester. And while the previous government gave out some limited but important powers over neighbourhood planning to local councils, these are only slowly being taken up, But the new communities and local government minister, Greg Clark, who had a city remit in his previous job, is a stronger supporter of localism than his predecessor Eric Pickles.

Local devolution may have powerful backing from the chancellor, but amid the debate over the EU referendum and more autonomy for Scotland, getting real power out to cities and regions may prove less easy than Leese and other city leaders would like.